The application generally relates to a speed control system for a compressor. The application relates more specifically to a speed control system for a compressor that can provide for adequate lubrication of the compressor bearings.
In certain compressors, the amount of lubrication oil that is provided to the bearings and other components of the compressor is related to the speed of the compressor, which is directly related to the frequency of current and voltage provided to the motor. In other words, the compressor receives more lubrication oil when operated at higher speeds (corresponding to higher voltage and current frequencies) and less lubrication oil when operated at lower speeds (corresponding to lower voltage and current frequencies). Typically, when the compressors are operated at lower speeds, the load on the compressor is not high and thus the corresponding requirement for lubrication oil is not high. However, when the compressor is operated at a lower speed and the load on the compressor increases, such as when the outdoor ambient temperature increases, the amount of lubrication oil provided by the lower speed operation may not provide enough protection for the compressor bearings.
Therefore what is needed is a control system for a compressor that can operate the compressor at an appropriate speed to provide a proper lubrication oil supply for the bearings and other components of the compressor.